10 Questions That Science Can't Answer Yet

Are We Alone in the Universe?

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There could be as many as 40 billion habitable planets in our galaxy alone. Estate of Stephen Laurence Strathdee/Getty Images

Some may think we're the only intelligent lifeforms in the universe. If that's the case, the universe is unimaginably lonely. Other researchers say there's almost no way that Earth is the only headquarters for life — there could be as many as 40 billion habitable planets just in our galaxy. That's an awful lot of potential for alien life.

There are some necessary requirements for life to arise. Not only does a planet need the right mix of elements and conditions, there also has to be a spark that gives rise to living creatures. Then, of course, those creatures have to somehow evolve into beings with intelligence.

Even to modern human science, the simplest of our planet's lifeforms are still an extremely complex stew of chemical reactions and cells. We don't really understand how they emerge, evolve and survive in an incredibly diverse range of environmental conditions. That makes finding, identifying and communicating with alien beings much more complicated.

In spite of those challenges, researchers at NASA think we may find traces of life in next couple of decades. More powerful telescopes could be one key to finding it.

Or it could be that life here is just a statistical aberration, an accident of the weirdest kind. Maybe this odd swamp of a planet really is a jewel of the universe, unduplicated and unlike any place else, anywhere.

Yet we know that water and similar gases and elements exist on many other planets. If we keep looking and happen to find even a shred of evidence, such as fossilized remains or tiny bacteria, it seems more likely that somewhere across the stars that another species is also looking to the heavens and pondering potential neighbors somewhere in the universe, too.